1. Field of the Invention
The present invention relates to a method, system, and program for maintaining backup copies of files in a backup storage device.
2. Description of the Related Art
In a client/server environment, a backup program, such as the International Business Machines Corporation (IBM) Tivoli Storage Management backup program,** maintains an image of the data and programs on a file server at a secondary storage, such as on tape cartridges. In the event of a system failure or other event that results in a loss of data on the file server, the backup program may be used to restore the data and programs from the tape cartridges to the file server.
One noticeable problem with such backup programs is the time required to perform the restore operation. In large network environments where multitudes of clients access the file server, the image of the file server may comprise several terabytes (one trillion bytes) of data. For such large file servers, the backup program can take one or more days to restore the entire image, i.e., all the programs and data, from the tape cartridges to the file server. Thus, the clients may not be able to access the file server for an extended period of time while the restore operation is performed.
One solution to optimize the restore operation is to utilize multiple tape drives to allow the files to be restored from multiple tape drives in parallel. Notwithstanding, for large file servers, the restoration time when several terabytes or more are involved can still extend an entire day.
Thus, there is a need in the art for improved techniques to operate a backup program in a manner that minimizes the time that the data is unavailable to the users during a restore operation.